界: Environment
本節包括原始程式碼之外的所有內容，但對於建立中產品的安全性仍至關重要。由於此領域所涵蓋的問題與原始程式碼沒有直接關係，因此我們將其與其他領域分開。
Race Condition: PHP Design Flaw
Abstract
PHP 配置選項
open_basedir 存在一個設計缺陷，使其容易發生檔案存取 race condition，這可能使攻擊者繞過 file system 上的 access control 檢查。Explanation
若啟用
此類攻擊針對的弱點大小視執行存取檢查和開啟檔案間的時間長短而定。即使連續執行呼叫，現今的作業系統也無法保證在處理程序讓出 CPU 之前執行的程式碼數量。攻擊者有許多技術來加長時間長度，使得盜取攻擊更加容易，但即使是很小的時間長度，此攻擊企圖也可以不斷的重複，直到成功為止。
open_basedir 配置選項，該選項會試圖阻止 PHP 程式對 php.ini 中所指定的目錄結構以外的檔案執行操作。雖然 open_basedir 選項可保證系統的安全性，但其執行方式卻受到 race condition 的不利影響，這可能會讓攻擊者在某些情況下略過該選項所定義的限制[2]。PHP 執行存取權限檢查和開啟檔案間，會存在 time-of-check、time-of-use (TOCTOU) race condition。與其他語言中 file system 的 race condition 相同，此弱點會讓攻擊者將指向透過 access control 檢查的 symlink 替換成另一個原來不能通過測試的檔案，以取得受保護檔案的存取權。此類攻擊針對的弱點大小視執行存取檢查和開啟檔案間的時間長短而定。即使連續執行呼叫，現今的作業系統也無法保證在處理程序讓出 CPU 之前執行的程式碼數量。攻擊者有許多技術來加長時間長度，使得盜取攻擊更加容易，但即使是很小的時間長度，此攻擊企圖也可以不斷的重複，直到成功為止。
References
[1] M. Achour et al. PHP Manual
[2] Stefan Esser PHP open_basedir Race Condition Vulnerability
[3] Artur Maj Securing PHP
[4] Emmanuel Dreyfus Securing Systems with Chroot
[5] Standards Mapping - Common Weakness Enumeration CWE ID 362, CWE ID 367
[6] Standards Mapping - Common Weakness Enumeration Top 25 2022 [22] CWE ID 362
[7] Standards Mapping - Common Weakness Enumeration Top 25 2023 [21] CWE ID 362
[8] Standards Mapping - DISA Control Correlation Identifier Version 2 CCI-000366, CCI-003178
[9] Standards Mapping - General Data Protection Regulation (GDPR) Access Violation
[10] Standards Mapping - NIST Special Publication 800-53 Revision 4 CM-6 Configuration Settings (P1), SA-11 Developer Security Testing and Evaluation (P1)
[11] Standards Mapping - NIST Special Publication 800-53 Revision 5 CM-6 Configuration Settings, SA-11 Developer Testing and Evaluation
[12] Standards Mapping - OWASP Application Security Verification Standard 4.0 1.11.2 Business Logic Architectural Requirements (L2 L3), 1.11.3 Business Logic Architectural Requirements (L3), 11.1.6 Business Logic Security Requirements (L2 L3)
[13] Standards Mapping - OWASP Top 10 2013 A5 Security Misconfiguration
[14] Standards Mapping - OWASP Top 10 2017 A6 Security Misconfiguration
[15] Standards Mapping - OWASP Top 10 2021 A04 Insecure Design
[16] Standards Mapping - Payment Card Industry Data Security Standard Version 4.0 Requirement 6.2.4, Requirement 7.3.2
[17] Standards Mapping - Payment Card Industry Data Security Standard Version 4.0.1 Requirement 6.2.4, Requirement 7.3.2
[18] Standards Mapping - Payment Card Industry Software Security Framework 1.1 Control Objective B.3.3 - Terminal Software Attack Mitigation
[19] Standards Mapping - Payment Card Industry Software Security Framework 1.2 Control Objective B.3.3 - Terminal Software Attack Mitigation
[20] Standards Mapping - SANS Top 25 2009 Insecure Interaction - CWE ID 362
[21] Standards Mapping - SANS Top 25 2010 Insecure Interaction - CWE ID 362
[22] Standards Mapping - Security Technical Implementation Guide Version 3.1 APP3630.1 CAT II
[23] Standards Mapping - Security Technical Implementation Guide Version 3.4 APP3630.1 CAT II
[24] Standards Mapping - Security Technical Implementation Guide Version 3.5 APP3630.1 CAT II
[25] Standards Mapping - Security Technical Implementation Guide Version 3.6 APP3630.1 CAT II
[26] Standards Mapping - Security Technical Implementation Guide Version 3.7 APP3630.1 CAT II
[27] Standards Mapping - Security Technical Implementation Guide Version 3.9 APP3630.1 CAT II
[28] Standards Mapping - Security Technical Implementation Guide Version 3.10 APP3630.1 CAT II
[29] Standards Mapping - Security Technical Implementation Guide Version 4.2 APSC-DV-001995 CAT II
[30] Standards Mapping - Security Technical Implementation Guide Version 4.3 APSC-DV-001995 CAT II
[31] Standards Mapping - Security Technical Implementation Guide Version 4.4 APSC-DV-001995 CAT II
[32] Standards Mapping - Security Technical Implementation Guide Version 4.5 APSC-DV-001995 CAT II
[33] Standards Mapping - Security Technical Implementation Guide Version 4.6 APSC-DV-001995 CAT II
[34] Standards Mapping - Security Technical Implementation Guide Version 4.7 APSC-DV-001995 CAT II
[35] Standards Mapping - Security Technical Implementation Guide Version 4.8 APSC-DV-001995 CAT II
[36] Standards Mapping - Security Technical Implementation Guide Version 4.9 APSC-DV-001995 CAT II
[37] Standards Mapping - Security Technical Implementation Guide Version 4.10 APSC-DV-001995 CAT II
[38] Standards Mapping - Security Technical Implementation Guide Version 4.11 APSC-DV-001995 CAT II
[39] Standards Mapping - Security Technical Implementation Guide Version 4.1 APSC-DV-001995 CAT II
[40] Standards Mapping - Security Technical Implementation Guide Version 5.1 APSC-DV-001995 CAT II
[41] Standards Mapping - Security Technical Implementation Guide Version 5.2 APSC-DV-001995 CAT II
[42] Standards Mapping - Security Technical Implementation Guide Version 5.3 APSC-DV-001995 CAT II
[43] Standards Mapping - Security Technical Implementation Guide Version 6.1 APSC-DV-001995 CAT II
[44] Standards Mapping - Security Technical Implementation Guide Version 6.2 APSC-DV-001995 CAT II
desc.structural.php.race_condition_php_design_flaw